1. Field of the Invention
The present invention relates to an ink jet type recording head in which a piezoelectric vibrator or other pressure generating means is provided in a region of a pressure generating chamber communicating with a nozzle opening. Ink drops are generated when the pressure generating chamber is compressed by the deflection vibration of the piezoelectric vibrator.
2. Description of the Related Art
In order to conduct printing at high speed and high density, it would be desirable to increase the number of nozzle openings per recording head. Since an ink jet type recording head requires as many pressure applying means for applying pressure to ink as the number of nozzle openings and requires uniform pressure applying performance, the pressure applying means may be in the lowest production yield among head forming members.
In order to overcome this problem, the following recording head forming technique has been adopted. A pressure generating unit of a recording head is designed to have a comparatively small number of pressure generating means, and a plurality of such pressure generating units are arranged in a main scanning direction on a relatively easily manufacturable passage unit that has nozzle openings, reservoirs, and the like. Accordingly, the recording head can be formed with a large number of nozzle openings.
However, in this design, the thickness of the walls of adjacent pressure generating units is larger than a nozzle opening arraying pitch. Therefore, the pressure generating units must be arranged so as to be shifted by the width of a single unit, which in turn imposes the problem that the width of the recording head becomes about twice as much as the width of the pressure generating unit. In addition, only a small inclination produced at the time of -attaching the recording head to the recording apparatus lead to a grave error in the dot forming position between nozzle openings for black ink and nozzle openings for color inks, and this grave error greatly affects print quality. Therefore, highly accurate positioning is required for pressure generating unit assembling operation, which in turn makes the assembling operation difficult.
In the present invention, an ink jet type recording head comprising a plurality of pressure generating units, each the pressure generating unit comprising: a pressure generating means; a plurality of pressure generating chambers for pressurizing ink through actuation of the pressure generating means; a plurality of pressure generating units housing the pressure generating chambers; and a passage unit on which the pressure generating units are arranged, the passage unit having reservoirs formed therein, at least one reservoir extending so as to cross over a plurality of pressure generating units; in which
the pressure generating chambers are arranged in line along an arrangement direction;
the pressure generating chambers are inclined at an angle xcex8 with respect to the arrangement direction; outer walls of the pressure generating units in the arrangement direction are inclined at an angle xcex8 with respect to the arrangement direction, thereby providing an inclination for of the pressure generating units; the pressure generating units are arranged on the passage unit such that each pressure generating unit is shifted in a sheet forward direction along the inclination of an adjacent one of the pressure generating units away from a position aligned with the adjacent pressure generating unit; and an amount of shift between each pressure generating unit and the adjacent pressure generating unit is set such that a pitch (hereinafter referred to as the xe2x80x9cdesign pitchxe2x80x9d whenever applicable) between first opposing ones of the pressure generating chambers that oppose each other across the outer walls of the pressure generating unit and the adjacent pressure generating unit is equal to a pitch between second opposing ones of the pressure generating chambers that oppose each other on the pressure generating unit.
Since the outer walls of the opposing pressure generating units are inclined with respect to a line orthogonal to a pressure generating chamber arraying direction, a nozzle opening arraying pitch at a boundary region between the opposing pressure generating units can be adjusted to the design pitch by shifting one of the opposing pressure generating units in parallel along the outer walls thereof. That is, if one of the opposing pressure generating units is shifted in parallel along the outer walls thereof, the distance between the pressure generating chambers belonging to the opposing pressure generating units in the pressure generating chamber arraying direction is changed, so that the nozzle opening arraying pitch at the boundary region between the opposing pressure generating units can be adjusted to the design pitch. Since this shifted distance is extremely small compared with the width of each pressure generating unit, the width of the recording head as a whole can be made smaller than a product of the width of a pressure generating unit and the number of pressure generating units arranged in the recording head moving direction.
Therefore, a first object of the invention is to provide an ink jet type recording head capable of increasing the number of nozzle openings per recording head using a plurality of units without significantly increasing the width of the recording head.
Further, a second object of the invention is to provide an ink jet type recording head capable of jetting a plurality of kinds of ink drops by providing a plurality of reservoirs, at least one reservoir communicating with a plurality of pressure generating units.
Still further, a third object of the invention is to provide a flexible cable capable of being connected to a plurality of actuators with ease.